Systems Mapping for Hematopoietic Progenitor Cell Heterogeneity

Cells with the same genotype growing under the same conditions can show different phenotypes, which is known as “population heterogeneity”. The heterogeneity of hematopoietic progenitor cells has an effect on their differentiation potential and lineage choices. However, the genetic mechanisms governing population heterogeneity remain unclear. Here, we present a statistical model for mapping the quantitative trait locus (QTL) that affects hematopoietic cell heterogeneity. This strategy, termed systems mapping, integrates a system of differential equations into the framework for systems mapping, allowing hypotheses regarding the interplay between genetic actions and cell heterogeneity to be tested. A simulation approach based on cell heterogeneity dynamics has been designed to test the statistical properties of the model. This model not only considers the traditional QTLs, but also indicates the methylated QTLs that can illustrate non-genetic individual differences. It has significant implications for probing the molecular, genetic and epigenetic mechanisms of hematopoietic progenitor cell heterogeneity.     

多肽融合标签的移除策略

多肽融合标签能够赋予目标蛋白新的特性,便于目标蛋白的定位、追踪、纯化以及结构和相互作用研究．但在很多情况下,尤其是研究蛋白质结构或分离纯化药用蛋白时,需要将多肽融合标签从融合蛋白上切除,以降低和消除多肽融合标签对目标蛋白结构和功能的影响．可用来切除多肽融合标签的方法主要有4种,即化学法、内切蛋白酶法、外切蛋白酶法以及自我剪切法．介绍和比较了每种方法的基本原理、应用以及研究进展．     

A systems-biology analysis of feedback inhibition in the Sho1 osmotic-stress-response pathway

BACKGROUND: A common property of signal transduction systems is that they rapidly lose their ability to respond to a given stimulus. For instance in yeast, the mitogen-activated protein (MAP) kinase Hog1 is activated and inactivated within minutes, even when the osmotic-stress stimulus is sustained. RESULTS: Here, we used a combination of experimental and computational analyses to investigate the dynamic behavior of Hog1 activation in vivo. Computational modeling suggested that a negative-feedback loop operates early in the pathway and leads to rapid attenuation of Hog1 signaling. Experimental analysis revealed that the membrane-bound osmosensor Sho1 is phosphorylated by Hog1 and that phosphorylation occurs on Ser-166. Moreover, Sho1 exists in a homo-oligomeric complex, and phosphorylation by Hog1 promotes a transition from the oligomeric to monomeric state. A phosphorylation-site mutation (Sho1(S166E)) diminishes the formation of Sho1-oligomers, dampens activation of the Hog1 kinase, and impairs growth in high-salt or sorbitol conditions. CONCLUSIONS: These findings reveal a novel phosphorylation-dependent feedback loop leading to diminished cellular responses to an osmotic-stress stimulus.     

Genetic analysis of IREB2, FAM13A and XRCC5 variants in Chinese Han patients with chronic obstructive pulmonary disease

Recently, variants (rs2568494, rs2869967 and rs3821104) in the IREB2, FAM13A and XRCC5 genes were found to be associated with chronic obstructive pulmonary disease (COPD) in non-Asian populations by genome-wide association study (GWAS) analysis. To evaluate whether variants in these genes are related to COPD in Chinese Han population, we investigated COPD patients of Chinese Han ethnicity from Mainland China. Significant differences in genotypic distributions (χ² = 6.319, p = 0.042 for rs2869967; χ² = 6.062, p = 0.048 for rs3821104) and allele distributions (χ² = 4.014, p = 0.045 for rs2869967; χ² = 5.607, p = 0.018 for rs3821104) were observed between patients and control subjects for variants rs2869967 and rs3821104, whereas no statistically significant associations for genotypic and allelic distribution between IREB2 rs2568494 and COPD phenotype (p > 0.05) were identified. Our results support that FAM13A rs2869967 and XRCC5 rs3821104 are associated with COPD in Chinese Han population.     

Role of phosphodiesterase in cyclic AMP signaling in cultured rat granulosa cells

Inactivation of the cyclic nucleotide signal in granulosa cells depends on a complex array of cyclic nucleotide phosphodiesterases (PDE). In order to examine the role of PDE in cyclic AMP (cAMP) signaling in granulosa cells, the present study examined the expression of PDE4D proteins and regulation of cAMP-PDE activities in cultured rat granulosa cells. The results of immunoblot analyses showed that two predominant PDE4D subtypes of approximately 80 and 70 kDa appeared when immature rat granulosa cells were treated with FSH. However, these two new subtypes presumed to be PDE4D proteins were not influenced by treatments of DETA/NO, cGMP and PKB inhibitor, LY294002. Immature rat granulosa cells treated with medium alone displayed low cAMP-PDE activity throughout 48 h of culture while those treated with FSH (2 ng.mL-1) showed a marked increase in cAMP-PDE activity between 6 and 12 h of culture, followed by a decline. The findings from the present study indicate that the increased cAMP-PDE activity by FSH is mainly related to the changes of PDE4D protein levels. However, the inhibitory effects of NO on cAMP accumulation in rat granulosa cells are not via the increased cAMP-PDE activity.     

A study of conservation genetics in Cupressus chengiana, an endangered endemic of China, using ISSR markers

ISSR markers were used to analyze the genetic diversity and genetic structure of eight natural populations of Cupressus chengiana in China. ISSR analysis using 10 primers was carried out on 92 different samples. At the species level, 136 polymorphic loci were detected. The percentage of polymorphic bands (PPB) was 99%. Genetic diversity (He) was 0.3120, effective number of alleles (Ae) was 1.5236, and Shannon's information index (I) was 0.4740. At the population level, PPB = 48%, Ae = 1.2774, He = 0.1631, and I = 0.2452. Genetic differentiation (Gst) detected by Nei's genetic diversity analysis suggested 48% occurred among populations. The partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (54%) and among populations (46%; P < 0.0003). The average number of individuals exchanged between populations per generation (Nm) was 0.5436. Samples from the same population clustered in the same population-specific cluster, and two groups of Sichuan and Gansu populations were distinguishable. A significantly positive correlation between genetic and geographic distance was detected (r = 0.6701). Human impacts were considered one of the main factors to cause the rarity of C. chengiana, and conservation strategies are suggested based on the genetic characters and field investigation, e.g., protection of wild populations, reestablishment of germplasm bank, and reintroduction of more genetic diversity.     

基于多目标灰色局势决策的三峡库区防护林类型空间优化配置

基于2007年Landsat TM遥感影像和影响防护林的主导环境因子,对三峡库区的森林立地进行分类,并通过选取水源涵养量、生物量和林分生产力3个指标,利用多目标灰色局势决策模型对库区现有的针叶林、阔叶林、针阔混交林和灌木林4种防护林类型进行空间优化配置.结果表明： 2007年,三峡库区森林立地可划分为40种类型;空间配置优化后,研究区针叶林、阔叶林、针阔混交林和灌木林的面积比例分别为32.55%、29.43%、34.95%和3.07%.与优化前相比,优化后针叶林和灌木林的面积比例分别减少了8.79%和28.55%,阔叶林和针阔混交林分别增加了10.23%和27.11%.通过防护林类型的空间优化,三峡库区整体的水源涵养能力、生物量和林分生产力分别增加14.09×10⁸ m³、0.35×10⁸ t和1.08×10⁶ t.     

A Tyrosine-based Motif Localizes a Drosophila Vesicular Transporter to Synaptic Vesicles in Vivo

Vesicular neurotransmitter transporters must localize to synaptic vesicles (SVs) to allow regulated neurotransmitter release at the synapse. However, the signals required to localize vesicular proteins to SVs in vivo remain unclear. To address this question we have tested the effects of mutating proposed trafficking domains in Drosophila orthologs of the vesicular monoamine and glutamate transporters, DVMAT-A and DVGLUT. We show that a tyrosine-based motif (YXXY) is important both for DVMAT-A internalization from the cell surface in vitro, and localization to SVs in vivo. In contrast, DVGLUT deletion mutants that lack a putative C-terminal trafficking domain show more modest defects in both internalization in vitro and trafficking to SVs in vivo. Our data show for the first time that mutation of a specific trafficking motif can disrupt localization to SVs in vivo and suggest possible differences in the sorting of VMATs versus VGLUTs to SVs at the synapse.     

版纳省藤的组织培养

以版纳省藤的萌蘖芽为试材,从取材、材料的处理、外植体的诱导分化、芽的增殖、生根以及影响试管苗形成几个重要因素等方面探讨了版纳省藤组织培养和快速繁殖的技术和方法,获得了生长素与细胞分裂素对芽的诱导分化及芽的增殖最佳配比浓度。以改良MS为基本培养基,在增殖培养基中添加0.5mg·L-1NAA、0.5mg·L-1KT和0.1mg·L-1BA,产生的有效苗最多;在生根培养基中添加1.5～2.0mg·L-1IBA生长素有利于版纳省藤组培苗生根。     

amiRNA分子设计及其离体合成策略

详细介绍了基于WMD3 (Web MicroRNA Designer 3) 软件平台的amiRNA (artificial microRNA)分子自动设计方法及其离体合成策略。应用网络在线设计时,只需输入目的基因靶序列相关信息后便可获得候选amiRNA。根据选定的最佳amiRNA,可得到四条含有amiRNA以及载体中miRNA 两侧序列的寡聚核苷酸序列。重叠延伸PCR合成策略可以以这四条序列以及根据质粒模板设计的A、B两段序列作为引物,扩增出目标amiRNA。同样尿嘧啶切除的策略也可合成amiRNA,但这些引物序列需做适当调整变动。此外,本文还介绍了基于特异引物退火的amiRNA合成策略,该策略可保证amiRNA分子能够一步PCR合成,合成后的amiRNA表达盒可通过合适的限制性位点被克隆至目的载体中的相应位点。可以预见,这种amiRNA分子设计的科学性与合成策略的精确性将会使amiRNAi技术在生物基因功能分析中发挥更加重要的作用,对生命科学研究产生深远的影响。